Loose-leaf documents and other sheet-like elements are often bound in a supporting binder. The loose-leaf documents are easily removed, and the binder is readily reused if the contents are no longer needed. Most commonly, three ring binders are used. These binders have a spine or base hingedly connected to a front and back cover. The spine or base may be a solid backing member to which a ring assembly is secured. Alternatively, the ring assembly may be secured to one of the covers immediately adjacent to a spine. The front and back covers may be formed of a relatively flexible material, or a relatively stiff material interconnected to the spine or base through a suitable flexible connection therebetween.
Other than having interior and exterior pockets for carrying loose sheets of paper, these types of binders are not designed to carry items often carried in a briefcase or backpack such as a book, notebook, calculator, cellular phone, notebook computer, palm top computer, key chain, and office supply items such as a pen, tape, marker, ruler, and etc. To accommodate these items, students usually carry their books and other school related items to/away from campus in a backpack. While on campus, the student has no need for the backpack because most of the items are left in a campus locker during the school day. Usually, only a binder and several additional items are needed for a particular class, and accordingly the student must either take the bulky backpack to class, or cram the needed extra items into his/her pockets or in the three ring binder. In another example, professionals generally carry a briefcase to/away from the office but would prefer to attend meetings with only a binder and a few additional items such as a cellular phone, small calculator, and a few key papers.